Door unit for heat treating apparatus

ABSTRACT

Opposing openings in two-walled enclosures of heat treating furnaces are closed by two doors which are mounted on a common carriage for movement first vertically across the openings and then laterally into pressing engagement with the walls of the enclosures. One of the doors is mounted for lateral floating on the carriage and is spring-biased away from the carriage to enable such door to adjust automatically to the position of the respective enclosure without interfering with continued movement of the carriage and the other door.

United States Patent [72] lnventor James C. Gaede Belvidere, Ill.

[21 Appl. No. 839,382

[22] Filed July 7, 1969 [45] Patented Jan. 26, 1971 [73] Assignee Alco Standard Corporation Valley Forge, Pa. a corporation of Ohio [54] DOOR UNIT FOR HEAT TREATING APPARATUS 7 Claims, 6 Drawing Figs.

[52] US. Cl 263/36, 1 10/ 173 [51] Int. Cl F27b 9/02, F23m 7/00 [50] Field of Search 263/36, 37, 38,39; 110/173 [56] References Cited UNITED STATES PATENTS 802,517 10/1905 Kugel 263/37 1,007,478 10/191 1 Murray 1 10/173X 3,257,976 6/1966 Bregman 110/173 3,399,875 9/ 1968 Ipsen 263/36 3,410,547 1 H1968 Bielefeldt.

Primary Examiner-John J. Camby Attorney-Wolfe, Hubbard, Leydig, Voit and Osann ABSTRACT: Opposing openings in two-walled enclosures of heat treating furnaces are closed by two doors which are mounted on a common carriage for movement first vertically across the openings and then laterally into pressing engagement with the walls of the enclosures. One of the doors is mounted for lateral floating on the carriage and is springv biased away from the carriage to enable such door to adjust automatically to the position of the respective enclosure without interfering with continued movement of the carriage and the other door.

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PATENTEU JAN26 I971 saw 2 OF 2 W llkww Mr M w DOOR UNIT F OR HEAT TREATING APPARATUS BACKGROUND OF THE INVENTION This invention relates to apparatus for treating workpieces and, more particularly, to a door unit for apparatus of the general type shown in US. Pat. No. 3,399,875 to lpsen, in which a door is disposed between two-spaced work chambers defined by walled enclosures and is mounted on a carriage by parallel links for movement first across an opening in one of the enclosures and then for lateral movement into engagement with the wall of the enclosure to tightly close the opening.

SUMMARY OF THE INVENTION The primary aim of the present invention is to provide a new and improved door unit of the above character in which a second door is attached to the same carriage to close an opening in the second enclosure, the second door being mounted in a unique manner to move laterally into tight engagement with the second enclosure without interfering with movement of the first door and regardless of variations in the spacing between the two enclosures. A more detailed object is to achieve the foregoing by mounting the second door for lateral floating relative to the carriage with lost-motion connections so that the second door may shift laterally into engagement with the second enclosure and then adjust automatically relative to the carriage to enable the latter to continue to move and shift the first door laterally into engagement with the first enclosure.

The invention also resides in the novel incorporation of the lost-motion connections into the parallel links which attach the second door to the carriage and in the novel construction of the connections to mount the second door for lateral floating while urging such door into tight pressing engagement with the second enclosure.

Other objects and advantages of the invention will become apparent from the following detailed description when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a fragmentary cross section taken vertically through a heat treating apparatus equipped with a new and improved door unit embodying the novel features of the present invention.

FIG. 2 is a cross section taken substantially along the line 2-2 of FIG. 1.

FIG. 3 is a cross section taken substantially along the line 3-3 of FIG. 2.

FIG. 4 is an enlarged view of parts illustrated in FIG. 2 with certain elements being broken away and shown in section.

FIG. 5 is a cross section taken vertically through one of the links and lost-motion connections.

FIG. 6 is a fragmentary perspective view of the door unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings for purposes of illustration, the invention is embodied in a heat treating apparatus in which workpieces 10 (FIG. 1) carried on cars 11 are heated in a preheat chamber 13 to temperatures ranging between 800 and 1,000 F. and then are transferred into a high heat chamber 14 for heating to a temperature as high as 3,000 F. In each chamber, the workpieces are heated in the presence of a high vacuum or a protective gas to prevent oxidation of the surfaces of the workpieces.

Herein, the chambers 13 and 14 are defined by internal enclosures 15 and 16 made of refractory material and housed within cylindrical gastight vessels 17 and 18 which are disposed in spaced end-to-end relation. The enclosures are generally rectangular in cross section and include opposing end walls 19 and 20 which are formed with aligned openings 21 and 22 permitting passage of the workpieces 10 and the cars 11 between the chambers. Heating elements (not shown) are housed within the enclosures to raise the temperature of the chambers.

Sandwiched between and interconnecting the vessels 17 and 18 is a gastight casing 23 formed by a top wall 24 (FIGS. 1 and 3), sidewalls 25, end walls 26 and 27 and a bottom wall 29. Adjacent the upper portions of the vessels, the sidewalls are formed with inwardly offset portions 30 (FIG. 4) which are connected at their lower ends to the bottom wall, the latter being curved generally in accordance with the curvature of the vessels. Attached rigidly to the end wall 26 and the bottom wall is a ringlike wall or bulkhead 31 (FIGS. 1, 3 and 4) which faces the end of the vessel 17 and which is formed with a workpiece-admitting opening or passageway 33 (FIG. 1) aligned with the opening 21 in the internal enclosure 15. On the other end wall 27 is a circular ring 34 formed with a passageway 35 which is aligned with the opening 22 in the enclosure 16. The bulkhead and the ring are disposed face-toface with annular flanges 36 encircling the ends of the vessels l7 and 18 and are detachably connected to the flanges by threaded bolts 37 (FIG. 1) which extend through holes formed through sets angularly spaced and angularly aligned ears 39 projecting radially from the bulkhead, the ring and the flanges. Sealing gaskets (not shown) extend around and between the flanges and the bulkhead and the ring to establish a gastight seal between the vessels 17 and 18 and the casing 23.

In order to enable the drawing of a vacuum or the introduction of a nonoxidizing gas selectively into the chambers 13 or 14, the two chambers must be sealed from one another to isolate the atmosphere in each chamber from that in the other chamber. This is accomplished trough the use of a sealing door 40 (FIGS. I and 6) which is adapted to be moved to a closed position sealing the passageway 33 in the bulkhead 31. In addition, a heat shielding door 41 is used to close the opening 21 in the internal enclosure 15 so as to block the escape of heat from the preheat chamber 13 during heating of the workpieces 10. As shown most clearly in FIG. 1, the doors are housed within the casing 23 alongside the bulkhead 31. The heat door 41 is made of heavy refractory material and herein is formed with a main closure section 43 sufficiently large to abut the end wall 19 of the enclosure 15 and with an inset section 44 sized to fit within the opening 21. The sealing door 40 is made of relatively lightweight material such as aluminum and, in this instance, is attached to the main section 43 of the heat door and, when in a tightly-sealed position (FIG. 1), engages the inner face of the bulkhead to seal the passageway 33 and isolate the atmosphere in the preheat chamber 13 from that in the casing 23 and the high heat chamber 14. A sealing gasket (not shown) is attached to the sealing door to insure the establishment of a gastight seal between the door and the bulkhead.

Advantageously, the sealing door 40 and the heat door 41 are mounted to move first vertically to closed positions extending across the passageway 33 and the opening 21 and then to move laterally or broadwise to positions in which the sealing door engages and seals against the bulkhead 31 and in which the heat door abuts and engages the end wall 19 of the enclosure 15. For these purposes, the doors are mounted on a carriage in the form of a yoke 45 which is guided for up and down movement in the casing 23. The doors move downwardly with the yoke to their closed positions and, as the yoke approaches the end of its downward travel, the doors are shifted laterally toward the bulkhead 31 and the enclosure 15. As the yoke is moved upwardly, the doors first are moved laterally away from the bulkhead and the enclosure and then move upwardly with the yoke to open positions located above the passageway 33.

More particularly, the yoke 45 comprises a transversely extending crosshead 46 to the ends of which are connected depending side members 47 (FIGS. 4 and 6). The latter carry vertically spaced rollers 49 which ride in center tracks 50 (FIG. 1) fastened to the offset portions 30 of sidewalls 25 to guide the yoke for up and down movement. Vertical shifting of the yoke is effected by two hydraulic actuators 51 (FIGS. 2

and 4) mounted along the outer sides of the offset portions 30 of the sidewalls and having rods 53 projecting into the casing 23 and connected to opposite ends of the crosshead 46. The actuators project through and are sealed to horizontal walls 54 (FIG. 4) connecting the sidewalls 25 with the offset wall portions 30, and thus the casing 23 is maintained in a gastight condition. As the rods are extended and retracted, the yoke is raised and lowered.

The sealing door 40 and the heat door 41 are connected pivotally to the yoke 45 by pairs of upper and lower parallel links 55 (FIG. 6) attached to and extending outwardly from the side members 47 of the yoke. As shown most clearly in FIG. 6, each link is connected pivotally at one end to one of the side members 47 by a pin 56 and is connected pivotally at its other end to one side edge of the sealing door 40 by a pin 57. Rollers 59 are joumaled on the pins 57 and ride within generally upright side tracks 60 (FIG. 1) fastened to the offset portions 30 of the sidewalls 25 alongside the center tracks 50. At their lower end portions, the side tracks are curved downwardly and away from the yoke 45 as indicated at 61 in FIG. 1.

As the yoke 45 is shifted downwardly by the actuators 51, the straight upright portions of the side tracks 60 guide the sealing door 40 and the heat door 41 for downward movement in a generally vertical path until the doors reach positions aligned with and extending across the opening 21 and the passageway 33. With continued downward movement of the yoke, the rollers 59 ride into curved portions 61 of the side tracks to cause the links 55 to swing outwardly away from the yoke and thereby shift the doors laterally of the yoke in parallel relation thereto. The sealing door 40 thus is pressed broadwise into tight-sealing engagement with the bulkhead 31 while the main section 43 of the heat door 41 is abutted tightly against the end wall 19 of the enclosure to block the escape of heat from the opening 21 in the preheat chamber 13.

When the sealing door is pressed tightly against the bulkhead, further outward swinging of the links is prevented thus stopping the downward movement of the yoke. The end wall 19 of the enclosure 15 is fixed rigidly to the vessel 17 to maintain a constant spacing between the end wall and the bulkhead 31 and thus, even as the enclosure expands and contracts during a heating cycle and during service use, the doors 40 and 41 may tightly engage both the end wall and the bulkhead. The other end of the enclosure 15 is free and may shift to accommodate expansion and contraction of the enclosure.

Opening of the doors 40 and 41 is effected by raising the yoke 45 with the actuators 51. As the yoke raises, the rollers 59 first ride into the curved portions 61 of the side tracks 60 to cause the doors to shift broadwise away from the bulkhead 31. When the rollers ride into the straight portions of the tracks, the links 55 swing inwardly toward the yoke to cause the doors to be lifted vertically with the yoke.

In accordance with the present invention, a second laterally shiftable heat door 65 for closing the opening 22 in the enclosure 16 is carried on the yoke 45 and is mounted to float relative to the yoke so as to be able to press tightly against the end wall of the enclosure without restricting any further downward movement of the yoke needed to shift the doors 40 and 41 into engagement with the bulkhead 31 and the enclosure 15. To these ends, the heat door 65 is attached to the yoke by pivoted parallel links 66 (FIG. 6) and by resiliently yieldably lost-motion connections 67 which, after the door 65 shifts laterally into engagement with the end wall 20, press the door against the end wall while enabling the links 66 to continue to swing outwardly to allow further downward movement of the yoke. As a result, the end wall 20 may be left free to shift during expansion and contraction of the enclosure 16 and yet the single yoke 45 may be used to effect lateral shifting of all of the doors 40, 41 and 65 into tightly closed positions even though the position of the end wall 20 changes.

More specifically and as shown most clearly in FIG. 1, the heat door 65 is located on the side of the yoke 45 opposite the heat door 41 and is formed with a main section 70 and an inset section 71 of refractory material. Similar to the door 41, the inset section 71 is sized to fit within the enclosure opening 22 with the main section abutting the end wall 20.

The links 66 extend from the side members 47 of the yoke oppositely of the links 55 and are connected pivotally at their inner ends to the side members by pins 73 (FIG. 6). The lostmotion connections 67 are located at the outer ends of the links 66 and each connection herein comprises a plunger 75 (FIGS. 5 and 6) connected pivotally at its outer end to the door 65 by a pin 76 and telescoped slidably into a hole or bore 77 opening out of the outer end of each link. The pins rotatably support rollers 79 which ride within a second set of side tracks 80 (FIG. 1) secured to the offset portions 30 of the sidewalls 25 alongside the center tracks 50 and formed with downwardly curved lower end portions 81. At its inner end, each plunger is formed with a stem 83 (FIG. 5) of reduced diameter which fits slidably in a counterbore 84 in the link 66. A coil spring 85 is telescoped over the stem and into the bore 77 and is compressed between the plunger and a shoulder formed by the counterbore 84. The springs thus urge the plun gers outwardly from the links to bias the door 65 away from the yoke 45 but enable the door to float broadwise or laterally toward the yoke. The degree of extension of each plunger is limited by a dog point setscrew 86 (FIG. 5) threaded into the surrounding link and fitted slidably into an axially extending keyway 87 formed in the plunger.

To most clearly explain the operation of the foregoing arrangement, let it be assumed that the enclosure 16 has permanently expanded or grown after repeated heating cycles such that the spacing between the end wall 20 and the side tracks 80 is somewhat less than the spacing between the end wall 19 and the side tracks 60. Initially and with the yoke 45 in its raised position, thesprings 85 force the plungers 75 outwardly to their limit positions to bias the door 65 away from the yoke.

When the yoke 45 is lowered, the doors 40, 41 and 65 move downwardly together and then start shifting laterally in unison as the rollers 59 and 79 ride into the curved portions 61 and 81 of the tracks 60 and 80 to swing the links 55 and 66 out wardly. Because of the shifted position of the expanded end wall 20, the heat door 65 laterally engages such wall before the yoke has lowered sufficiently far to shift the doors 40 and 41 into engagement with the bulkhead 31 and the end wall 19. Since the door 65 is mounted for lateral floating, however, engagement of the door does not lock the links 66 against further outward swinging to prevent continued downward movement of the yoke 45. Instead, the plungers 75 slide inwardly into the links 66 thus decreasing the effective length of the links and allowing the latter to continue to swing outwardly. Accordingly, the yoke may proceed to move downwardly as far as necessary to shift the doors 40 and 41 broadwise into tight engagement with the bulkhead 31 and the end wall 19. At the same time, the springs 85 keep the door 65 pressed tightly against the end wall 20 to block the escape of heat from the high heat chamber 14.

From the foregoing, it will be apparent that the present invention brings to the art a new and improved door unit with at least two oppositely facing doors 41 and 65 mounted on a common yoke 45 and capable of shifting laterally into tight engagement with end-toend walls regardless of changes in the lateral spacing between the walls. Thus, the floatably-mounted door 65 is capable of adjusting automatically to accommodate expansion and shifting of the enclosure 16 and also is capable of tightly closing the enclosure even if its own dimensions change as a result of expansion and contraction.

I claim:

1. In apparatus for heat treating workpieces, the combination of, two work chambers aligned end-to-end and having opposing end walls spaced from one another and defining first and second openings permitting passage of the workpieces between the chambers, a door unit disposed between said walls and comprising a carriage mounted for movement in opposite directions in a path parallel to said walls, first and second doors disposed on opposite sides of said carriage for closing the respective openings, first and second sets of pivoted parallel links extending in opposite directions from said carriage and connecting the respective doors to the carriage, mechanism for moving said carriage along said path to move said doors parallel to said path from open positions with respect to said openings to closed positions aligned with said openings, means operable when said doors reach said closed positions to cause shifting of said doors laterally of said path and toward face-to-face engagement with said walls in response to continued movement of said carriage, and means connected to the links of said first set for mounting said first door for bodily floating toward and away from said carriage and for biasing said first door away from said carriage thereby to enable the first door to pressably engage the adjacent wall while still allowing continued movement of the carriage to shift the second door laterally into engagement with its adjacent wall.

2. Apparatus as defined in claim 1 in which each link of said first set is pivoted at one end to said carriage, said last-mentioned means comprising plungers connected slidably to the other ends of said first links and connected pivotally to said first door, and springs acting between said first links and said plungers and urging the latter away from the first links.

3. Apparatus as defined in claim 2 in which said first links and said plungers are telescoped together with a sliding fit, said springs being telescoped with said plungers and being compressed between the plungers and the first links.

4. Apparatus as defined in claim 2 further including holes opening out of the other ends of said first links, said plungers being telescoped into said holes with a sliding fit, and said springs being telescoped into said holes and over said plungers and being compressed between the first links and the plungers.

5. Apparatus for treating workpieces and comprising a work chamber having a wall defining an opening accommodating passage of the workpieces, a carriage member mounted for movement alongside said wall in a path parallel to the wall, a door member disposed on one side of said wall for closing said opening, a set of parallel links extending between and pivoted relative to said members for connecting the door member to the carriage member, mechanism for moving said carriage member along said path to move said door member parallel to said path from a first position on one side of the opening to a second position aligned with and extending across the opening, and means operable when said door member reaches said second position to cause swinging of said links to shift said door member laterally of said path and toward face-to-face engagement with said wall in response to continued movement of said carriage member, the improvement in said apparatus comprising, resiliently yieldable lost-motion connections between said links and one of said members and mounting said door memberfor bodily floating toward said carriage member while urging the door member away from the carriage member thereby to enable the door member to pressably engage said wall without restricting continued movement of said carriage member along said path.

6. Apparatus as defined in claim 5 in which each of said links is pivoted at one end to one of said members, said lostmotion connections comprising plungers connected slidably to the other ends of said links and connected pivotally to the other of said members, and springs acting between said links and said plungers and urging the latter to slide away from the links.

7. apparatus for treating workpiece and comprising a work chamber having a wall defining an opening accommodating passage of the workpieces, a carriage mounted for movement alongside said wall in a path parallel to the wall, a door disposed on one side of said wall for closing said opening, means mounting said door for movement with said carriage first parallel to the latter to a closed position extending across said opening and then broadwise away from the carriage into face-to-face engagement with said wall, and a resiliently yieldable lost-motion connection between said carriage and said door and mounting said door for broadwise bodily floating toward said carriage wheel urging the door away from the carriage. 

1. In apparatus for heat treating workpieces, the combination of, two work chambers aligned end-to-end and having opposing end walls spaced from one another and defining first and second openings permitting passage of the workpieces between the chambers, a door unit disposed between said walls and comprising a carriage mounted for movement in opposite directions in a path parallel to said walls, first and second doors disposed on opposite sides of said carriage for closing the respective openings, first and second sets of pivoted parallel links extending in opposite directions from said carriage and connecting the respective doors to the carriage, mechanism for moving said carriage along said path to move said doors parallel to said path from open positions with respect to said openings to closed positions aligned with said openings, means operable when said doors reach said closed positions to cause shifting of said doors laterally of said path and toward face-to-face engagement with said walls in response to continued movement of said carriage, and means connected to the links of said first set for mounting said first door for bodily floating toward and away from said carriage and for biasing said first door away from said carriage thereby to enable the first door to pressably engage the adjacent wall while still allowing continued movement of the carriage to shift the second door laterally into engagement with its adjacent wall.
 2. Apparatus as defined in claim 1 in which each link of said first set is pivoted at one end to said carriage, said last-mentioned means comprising plungers connected slidably to the other ends of said first links and connected pivotally to said first door, and springs acting between said first links and said plungers and urging the latter away from the first links.
 3. Apparatus as defined in claim 2 in which said first links and said plungers are telescoped together with a sliding fit, said springs being telescoped with said plungers and being compressed between the plungers and the first links.
 4. Apparatus as defined in claim 2 further including holes opening out of the other ends of said first links, said plungers being telescoped into said holes with a sliding fit, and said springs being telescoped into said holes and over said plungers and being compressed between the first links and the plungers.
 5. Apparatus for treating workpieces and comprising a work chamber having a wall defining an opening accommodating passage of the workpieces, a carriage member mounted for movement alongside said wall in a path parallel to the wall, a door member disposed on one side of said wall for closing said opening, a set of parallel links extending between and pivoted relative to said members for connecting the door member to the carriage Member, mechanism for moving said carriage member along said path to move said door member parallel to said path from a first position on one side of the opening to a second position aligned with and extending across the opening, and means operable when said door member reaches said second position to cause swinging of said links to shift said door member laterally of said path and toward face-to-face engagement with said wall in response to continued movement of said carriage member, the improvement in said apparatus comprising, resiliently yieldable lost-motion connections between said links and one of said members and mounting said door member for bodily floating toward said carriage member while urging the door member away from the carriage member thereby to enable the door member to pressably engage said wall without restricting continued movement of said carriage member along said path.
 6. Apparatus as defined in claim 5 in which each of said links is pivoted at one end to one of said members, said lost-motion connections comprising plungers connected slidably to the other ends of said links and connected pivotally to the other of said members, and springs acting between said links and said plungers and urging the latter to slide away from the links.
 7. apparatus for treating workpiece and comprising a work chamber having a wall defining an opening accommodating passage of the workpieces, a carriage mounted for movement alongside said wall in a path parallel to the wall, a door disposed on one side of said wall for closing said opening, means mounting said door for movement with said carriage first parallel to the latter to a closed position extending across said opening and then broadwise away from the carriage into face-to-face engagement with said wall, and a resiliently yieldable lost-motion connection between said carriage and said door and mounting said door for broadwise bodily floating toward said carriage wheel urging the door away from the carriage. 